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Watts Relief Valve: FNPTF x FNPTF, 3/4 in x 3/4 in, Copper Silicon Alloy - ASME Section XIII Hot Water Pressure Relief Valves
WattsASME Section XIII Hot Water Pressure Relief Valves

Watts Relief Valve: FNPTF x FNPTF, 3/4 in x 3/4 in, Copper Silicon Alloy

The WATTS Relief Valve (MPN 3/4 LF174A 100 FS) is an ASME Section XIII hot water pressure relief valve with FNPTF x FNPTF connections, 3/4 in x 3/4 in size, constructed of Copper Silicon Alloy, and rated for 150 psi…

SKU 3G-OTH-442538

Also listed as: 34LF174A100FS · 3 4 LF174A 100 FS · 3-4-LF174A-100-FS

Brand
Watts
Item
Relief Valve: FNPTF x FNPTF, 3/4 in x 3/4 in, Copper Silicon Alloy
Category
ASME Section XIII Hot Water Pressure Relief Valves
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Technical Specifications

Watts
Manufacturer Part Number
3/4 LF174A 100 FS
Type
3/4 in x 3/4 in, Copper Silicon Alloy
Max. Op Pressure
150 psi

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Watts Products
3G Electric (S) Pte. Ltd. — Singapore

Product Description

The WATTS Relief Valve (MPN 3/4 LF174A 100 FS) is an ASME Section XIII hot water pressure relief valve with FNPTF x FNPTF connections, 3/4 in x 3/4 in size, constructed of Copper Silicon Alloy, and rated for 150 psi maximum operating pressure.

Frequently Asked Questions

What is the Watts LF174A relief valve used for?

The Watts LF174A is an ASME Section XIII hot water pressure relief valve used in commercial and industrial hydronic systems. It protects boilers, water heaters, and storage tanks from overpressure by automatically releasing water when system pressure exceeds 150 psi.

What are the specifications of the Watts 3/4 LF174A 100 FS?

This Watts relief valve has 3/4 inch FNPTF inlet and outlet connections, a copper silicon alloy body, and a maximum operating pressure of 150 psi. It is ASME Section XIII certified for hot water service. The manufacturer part number is 3/4 LF174A 100 FS.

Where to buy the Watts LF174A relief valve worldwide?

3G Electric supplies the Watts LF174A relief valve to customers worldwide. As a global industrial distributor, we handle full logistics, customs clearance, and delivery to your site. Contact us for pricing and lead time on this ASME-rated valve.

How to install a Watts pressure relief valve?

Install the Watts LF174A in the hot water system's tapping, ensuring the valve body is upright and discharge piping is directed to a safe drain. Use thread sealant on the FNPTF connections. Never install a shutoff valve between the relief valve and the system. Test operation after installation.

Used in

Common applications for Watts
Industrial burner gas safety systems — Watts HF2000 filters with GF-series seal kits maintain clean, regulated gas supply to burner pilot and main flame controls
Commercial heating and boiler installations — Modular filter assemblies support preventive maintenance and component replacement without full system shutdown
Process gas delivery pipelines — DN25 through DN125 filter bodies accommodate varying flow rates and inlet pressures across manufacturing and chemical processes
Gas pressure regulation benches — Multi-stage Watts filter platforms integrate with pressure reducers and safety shutoff valves in test and calibration environments
Equipment retrofit and upgrade projects — Available connection sizes and seal kits enable adaptation of newer Watts components into legacy gas control systems
Planned maintenance and spare-parts inventory — Filter seal kits allow facilities to stock consumables in advance, reducing downtime during scheduled gas system servicing

Watts Products

3G Electric supplies Watts asme section xiii hot water pressure relief valves. We supply genuine products with in-stock availability on common SKUs, technical documentation, commissioning support, and warranty service — worldwide.

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Compatible alternatives & equivalents

Cross-referenced by specification & description
WATTS Relief Valve: FNPTF x FNPTF, 3/4 in x 3/4 in, Copper Silicon Alloy, 150 psi Max. Op Pressure (MPN 3/4 LF174A 150 FS)
Watts
WATTS Relief Valve: FNPTF x FNPTF, 3/4 in x 3/4 in, Copper Silicon Alloy, 150 psi Max. Op Pressure (MPN 3/4 LF174A 150 FS)
WATTS Relief Valve: FNPTF x FNPTF, 3/4 in x 3/4 in, Copper Silicon Alloy, 150 psi Max. Op Pressure (MPN 3/4 LF174A 125 FS)
Watts
WATTS Relief Valve: FNPTF x FNPTF, 3/4 in x 3/4 in, Copper Silicon Alloy, 150 psi Max. Op Pressure (MPN 3/4 LF174A 125 FS)
WATTS Relief Valve: FNPTF x FNPTF, 2 in x 2 in, Bronze, 150 psi Max. Op Pressure (MPN 2 174A 100 FS)
Watts
WATTS Relief Valve: FNPTF x FNPTF, 2 in x 2 in, Bronze, 150 psi Max. Op Pressure (MPN 2 174A 100 FS)
WATTS Relief Valve: FNPTF x FNPTF, 1 in x 1 in, Copper Silicon Alloy, 150 psi Max. Op Pressure (MPN 1 LF174A 150 FS)
Watts
WATTS Relief Valve: FNPTF x FNPTF, 1 in x 1 in, Copper Silicon Alloy, 150 psi Max. Op Pressure (MPN 1 LF174A 150 FS)
WATTS Relief Valve: FNPTF x FNPTF, 2 in x 2 in, Bronze, 150 psi Max. Op Pressure (MPN 2 174A 150 FS)
Watts
WATTS Relief Valve: FNPTF x FNPTF, 2 in x 2 in, Bronze, 150 psi Max. Op Pressure (MPN 2 174A 150 FS)
WATTS Relief Valve: FNPTF x FNPTF, 1 1/4 in x 1 1/4 in, Copper Silicon Alloy, 8 1/2 in Overall Ht (MPN 1-1/4 LF174A 150 FS)
Watts
WATTS Relief Valve: FNPTF x FNPTF, 1 1/4 in x 1 1/4 in, Copper Silicon Alloy, 8 1/2 in Overall Ht (MPN 1-1/4 LF174A 150 FS)

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WATTS Relief Valve: FNPT x FNPT, 1 in x 1 in, Bronze, 94 psi Max. Op Pressure, 5 3/4 in Overall Ht (MPN 1 174A 125 FS)
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WATTS Relief Valve: FNPT x FNPT, 1 in x 1 in, Bronze, 94 psi Max. Op Pressure, 5 3/4 in Overall Ht (MPN 1 174A 125 FS)
WATTS Pressure Relief Valve: FNPTF x FNPTF, 1 1/2 in x 1 1/2 in, Copper Silicon Alloy (MPN 0121544)
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WATTS Relief Valve: FNPTF x FNPTF, 3/4 in x 3/4 in, Copper Silicon Alloy, 150 psi Max. Op Pressure (MPN 3/4 LF174A 75 FS)
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WATTS Relief Valve: FNPTF x FNPTF, 3/4 in x 3/4 in, Copper Silicon Alloy, 150 psi Max. Op Pressure (MPN 3/4 LF174A 75 FS)
WATTS Relief Valve: FNPTF x FNPTF, 2 in x 2 1/2 in, Iron, 75 psi Max. Op Pressure (MPN 2 740 030 FS)
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WATTS Relief Valve: FNPTF x FNPTF, 2 in x 2 1/2 in, Iron, 75 psi Max. Op Pressure (MPN 2 740 030 FS)
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WATTS RELIEF VALVE: NPTF x NPTF, 1 1/4 in x 1 1/2 in, Iron, 30 psi Max. Op Pressure (MPN F383025)
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WATTS RELIEF VALVE: NPTF x NPTF, 3/4 in x 3/4 in, Iron, 20 psi Max. Op Pressure, 3 1/2 in Overall Ht (MPN F358553)
WATTS Relief Valve: FNPTF x FNPTF, 1 1/2 in x 1 1/2 in, Bronze, 150 psi Max. Op Pressure (MPN 1-1/2 174A 150 FS)
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WATTS Relief Valve: FNPTF x FNPTF, 1 1/2 in x 1 1/2 in, Bronze, 150 psi Max. Op Pressure (MPN 1-1/2 174A 150 FS)